1. Field of the Invention
The present invention relates to polyalkylene terephthalate/polycarbonate compositions which contain a salt of a phosphinic acid, the use of the polyalkylene terephthalate/polycarbonate compositions for the production of mouldings and the mouldings themselves.
2. Description of Related Art
DE-A 19904814 describes thermoplastic moulding compositions containing 20-98 wt. % of a polyester, 1-50 wt. % of a polycarbonate, 1-40 wt. % of a phosphinic acid salt and/or of a diphosphinic acid salt and/or polymers thereof, and possible other additives.
EP 1 680 466 A1 describes the use of salts of hypophosphorous acid as flame retardants for polycarbonate compositions.
EP 2 225 320 A1 describes impact-modified polyalkylene terephthalate/polycarbonate compositions which contain a salt of phosphinic acid, wherein at a content of 20 parts by weight and more of component B, the flame retardancy no longer meets the necessary requirements.
JP-A 2001-261973 (Daicel Chemical Industries Ltd.) describes compositions of thermoplastic resins and inorganic and/or organic phosphinic acid salts. As an example, a combination of 51 wt. % PBT, 22 wt. % PC and 26 wt. % calcium phosphinate and 0.4 wt. % PTFE is mentioned.
The good effectiveness of organic, aromatic phosphates as flame retardants is countered by the disadvantage of the highly plasticising action of these compounds on the polymeric components, so that the heat resistance of these moulding compositions is unsatisfactory for many applications and other flame retardants are preferred.
Furthermore, it is known that polyesters often display inadequate flame retardancy and have a tendency towards very high moulding shrinkage, which makes it difficult to produce parts with tight tolerances.